1. Field of the Invention
The present invention relates to structures of an IC card in which a microcomputer and/or an IC memory are embedded in a plate such as a credit-card-sized plate.
2. Description of the Background Art
FIGS. 9A and 9B show a conventional IC card. FIG. 9A is a plan view of the IC card of a non-contact type, and FIG. 9B is a structural cross section taken along line C--C in FIG. 9B.
The IC card has the same size as that of credit cards, and incorporates an integrated circuit(s) such as a microprocessor and/or a memory. The IC card has advantages that a memory capacity is larger than those of a magnetic card or the like, and that information can be altered.
Referring to FIGS. 9A and 9B, an IC card 1 includes a pair of upper and lower casings 101 and 102, and a circuit board 4 assembled in the casings 101 and 102. On a surface of the circuit board 4, there are formed an IC (integrated circuit) device 5 as well as an interconnection pattern 9 connected to the IC device 5. The circuit board 4 is fixed to an internal surface of the lower casing 102. A space is formed between the circuit board 4 and an internal surface of the upper casing 101, and between the board and the internal surface of the lower casing 102.
FIGS. 10A and 10B illustrates a conventional IC card of another type. FIG. 10A is a structural plan view of the IC card of a contact type having an electrode terminal for an external connection, and FIG. 10B is a structural cross section taken along line D--D in FIG. 10A. The IC card of this type includes an electrode terminal 41 formed on a portion of the surface of the lower casing 102. The electrode terminal 41 is electrically connected to the interconnection pattern 9 on the circuit board 4 via a through hole 42.
The IC cards 1 of the non-contact and contact types described above have spaces 11 in casings 10 made from plastics. The space 11 must have the size large enough to prevent contact between the upper casing 101 and the IC device 5 when the card 1 is deformed to a large extent by an external force. Due to this large space 11, the IC card 1 cannot be made thin.
A strength of, particularly, the upper casing 101 depends only on the thickness of the upper casing 101. Therefore, in order to increase the strength of the IC card 1, the upper casing 101 and the lower casing 102 must have large thicknesses, respectively. This further impedes the reduction of thickness of the IC card.
Further, in the prior art IC card, moisture may enter through a gap between the upper and lower casings 101 and 102. Therefore, the prior art IC card has a problem of low environmental resistivity.
Meanwhile, IC cards having resin coating on the integrated circuit boards provided with the IC devices have been known.
U.S. Pat. No. 4,746,392 has disclosed an IC card in which an integrated circuit module is fitted into a portion of a stack of films which forms a card body. This card body is formed of a stacked structure of films without a frame member surrounding peripheries of these films. The card body has a concave portion. An IC module is fitted into this concave portion, and the gap between the IC module and the concave portion is filled with resin. This resin member covers only the periphery of the IC module, and does not serve as a structural member for the card body.
This IC card further employs a film covering a surface of the resin. Therefore, employment of this surface film impedes the reduction of thickness of the IC card. Further, since the card body is formed of the stacked structure of thin films, the card has low strength at its end or edge portions.